Contemporary architects have designed buildings to be ‘tighter’ to retain heat energy by eliminating drafts and air leakage. As such, there is a need to provide adequate ventilation into a building to offset contaminated air generated by chemicals and pollution inherent in the indoor environment. These pollutants include everything from household cleaners and other chemicals to outgases from laminated plywood and particle board construction materials. As such, a need has been established to provide fresh external air to be included in the air contained in a building.
In addition to tighter building construction, energy efficiency requirements have induced manufacturers to produce furnaces that convert as much fuel energy as possible into heat to be used in a building. By concentrating most of the heat energy within the furnace, the cooler exhaust gases cannot easily flow out of the chimney through convection. For this reason, furnace manufacturers have included a blower fan to expel the exhaust gases from the furnace and in most cases, to draw combustion air from outside the building.
To provide fresh air, many buildings include high efficiency ventilation systems that feature ‘heat recovery ventilators’ which recover heat energy through exchange of air from inside the building with air from outside the building by passing the air through a radiator type heat exchanger, an action designed to heat the air coming into the building with the radiant temperature of the air leaving the building as shown in U.S. Pat. No. 7,073,566, U.S. Pat. No. 6,450,244 and U.S. Pat. No. 6,575,228. These systems typically are stand alone designs that do not require action from the furnace or air conditioner to operate. Because of their exclusive function, these systems can be quite costly to purchase and install. None of the systems utilize the furnace combustion fan as a ventilation component to expel interior air from the building.
As a solution to this need for an efficient and inexpensive ventilation system, the present invention will provide fresh air introduction into a building while exhausting stale air from the building in a simple and cost effective manner.
Modern buildings that include forced air heating and cooling systems typically incorporate a high efficiency furnace to supply heat. Most high efficiency furnaces include a secondary heat exchanger which has the effect of reducing the temperature of the gases exhausted from the furnace combustion chamber. Because of the low temperature of the exhaust gases, these types of furnaces require a fan to supply air for furnace burner combustion and to remove the exhaust gases from the furnace to the exterior of the building, which is typically accomplished through a PVC pipe, while combustion air from outside of the building into the furnace is typically supplied through a second PVC pipe. In operation, outside air is drawn into the furnace combustion chamber, travels through the heat exchanger or exchangers and is ultimately exhausted through a PVC pipe to the outside of the building through the action of the exhaust fan included in the furnace.